Your vessel is loading bulk grain. As Master, what specific stability criteria apply to grain carriers under the International Grain Code, and how do you manage partly-filled holds?

A. INTERNATIONAL GRAIN CODE (MSC.23(59)) — STABILITY CRITERIA: THE GRAIN CODE APPLIES TO: bulk carrier loading grain (wheat, maize, soya, etc.). Unlike other bulk cargoes, grain has a known ANGLE OF REPOSE and heeling moment due to its free-surface behaviour. GRAIN CODE STABILITY CRITERIA: the International Grain Code specifies that throughout the voyage: (1) The GRAIN HEELING MOMENT must not exceed the RIGHTING MOMENT available at the prescribed angle of heel (typically 12°). The vessel must be able to demonstrate this using the approved calculation from the Document of Authorization; (2) THE RESIDUAL RIGHTING LEVER (remaining GZ) must be ≥ 0.075m at the angle of equilibrium with assumed shift; (3) THE RESIDUAL AREA under the GZ curve (between the angle of equilibrium and the lesser of 40° or the downflooding angle) must be ≥ 0.075 m·rad; (4) GM₀ AT DEPARTURE must be ≥ 0.30m (for grain — more stringent than IS Code's 0.15m); DOCUMENT OF AUTHORIZATION: the grain code requires the vessel to hold a Document of Authorization for the carriage of grain, issued by the flag state. The DOA specifies the approved loading arrangements and stability limits. PARTLY-FILLED (SLACK) HOLDS — VOID SPACE MANAGEMENT: grain in a partly-filled hold is particularly dangerous because grain can shift laterally (free surface effect of granular material). Requirements: (a) Partly-filled holds must be specifically addressed in the DOA; (b) Grain surface must be levelled and trimmed; (c) Strapping and securing of grain surface (bagging/locking) may be required; (d) Additional stability calculations for partly-filled hold configurations; (e) Generally: avoid partly-filled holds where possible — they require the most conservative stability assessment.

B. Grain is a standard dry bulk cargo. The IS Code intact stability criteria apply — no additional grain-specific criteria exist.

C. Partly-filled grain holds can be accepted without special stability calculation. The standard heeling moment calculation covers all loading configurations.

D. The International Grain Code is not mandatory. It provides guidance that the master may choose to follow.

A. IS CODE CRITERIA — GZ AT 30° DEFICIENCY: THE SIX IS CODE CRITERIA (MSC.267(85) — IS Code 2008): the International Stability Code mandates SIX stability criteria that ALL must be satisfied: (1) Area under GZ curve from 0° to 30° ≥ 0.055 m·rad; (2) Area under GZ curve from 0° to 40° ≥ 0.090 m·rad; (3) Area under GZ curve from 30° to 40° ≥ 0.030 m·rad; (4) GZ AT 30° ≥ 0.200m; (5) MAXIMUM GZ at angle ≥ 25°; (6) GM₀ ≥ 0.150m. FAILING ONE CRITERION MEANS FAILURE: all six criteria must be satisfied simultaneously. A GZ at 30° of 0.18m (vs required 0.20m) is a FAILURE — the vessel does NOT meet IS Code intact stability criteria. THE VESSEL CANNOT DEPART: it would be UNSEAWORTHY for the intended sea voyage. REMEDIES — HOW TO CORRECT THE DEFICIENCY: (1) REDUCE CARGO: if cargo is high in the vessel, shifting weight lower increases the GZ at 30°; (2) LOWER THE G: reduce KG by: (a) Adding low ballast (double bottom tanks); (b) Removing top-heavy weights; (c) Shifting cargo lower; (3) INCREASE BEAM LOADING: for certain hull forms, a different loading pattern affects the GZ curve shape; (4) REDUCE FREE SURFACE: if slack tanks are contributing to reduced GM — fill or empty tanks to remove free surface effect; DOCUMENTATION: the master must not sail with a stability calculation showing non-compliance. This is ISM non-conformity — notify DPA. LEGAL: departure with known stability non-compliance = MSA 1995 Section 58 offence (taking an unseaworthy ship to sea).

B. The vessel is close enough to the 0.20m requirement. A margin of 0.02m is within normal calculation tolerance and the vessel can depart.

C. Consult the charterer. As the cargo interests are driving the loading plan, the charterer is responsible for stability compliance.

D. Only the stability program minimum acceptable values matter for commercial voyages. IS Code criteria are guidelines, not mandatory requirements.

A. ANGLE OF LOLL vs LIST — IDENTIFICATION AND RESPONSE: DISTINGUISHING FEATURES: (1) LIST (caused by off-centre weight): (a) The vessel rests to one side; (b) GM is POSITIVE; (c) The GZ curve is displaced sideways but still positive; (d) Filling a tank on the high side (away from the list) will CORRECT the list; (e) The vessel has a definite "preferred" upright position but is offset by the asymmetric loading; (2) ANGLE OF LOLL (caused by NEGATIVE GM): (a) The vessel has ZERO or NEGATIVE GM; (b) The GZ at zero degrees is ZERO; (c) The vessel has no stable upright position — it lolls to one side where the GZ curve has positive values; (d) The vessel may flop between loll to port and loll to starboard; (e) IDENTIFYING CHARACTERISTIC: if you forcibly push the vessel further to the loll side — it continues to heel further. If you push a listed vessel — it resists and returns; HOW TO DISTINGUISH ON THE VESSEL: (1) Look at the GZ curve from the loading computer: is GM positive (list) or zero/negative (loll)?; (2) Apply a small external force: does the vessel resist (list) or comply (loll)?; CORRECT ACTION FOR LOLL: (1) DO NOT FILL HIGH-SIDE DOUBLE BOTTOM TANKS FIRST: the counter-intuitive nature of loll. Adding ballast on the high side RAISES the centre of gravity FURTHER — makes GM MORE negative — the loll worsens. The vessel may VIOLENTLY FLOP to the opposite side; (2) CORRECT ACTION: add ballast SYMMETRICALLY to the LOWEST point first. Fill lowest double bottom tanks evenly port and starboard to lower G and raise GM above zero; (3) NOTIFY DPA: this is a serious stability situation.

B. Fill the high-side (port) double bottom tanks immediately. Adding ballast to the high side always corrects any form of list or loll.

C. An 8° list at sea is normal and acceptable. No action is required unless the angle increases beyond 15°.

D. Open the cross-flooding valves to transfer ballast from the starboard to the port tanks. Cross-flooding always corrects asymmetric stability issues.